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Date: Thu, 23 Mar 2017 21:06:30 -0500
From: Rob Herring <robh@...nel.org>
To: gabriel.fernandez@...com
Cc: Mark Rutland <mark.rutland@....com>,
Russell King <linux@...linux.org.uk>,
Maxime Coquelin <mcoquelin.stm32@...il.com>,
Alexandre Torgue <alexandre.torgue@...com>,
Michael Turquette <mturquette@...libre.com>,
Stephen Boyd <sboyd@...eaurora.org>,
Nicolas Pitre <nico@...aro.org>, Arnd Bergmann <arnd@...db.de>,
daniel.thompson@...aro.org, andrea.merello@...il.com,
radoslaw.pietrzyk@...il.com, Lee Jones <lee.jones@...aro.org>,
devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org,
ludovic.barre@...com, olivier.bideau@...com, amelie.delaunay@...com
Subject: Re: [PATCH] clk: stm32h7: Add stm32h743 clock driver
On Wed, Mar 15, 2017 at 10:23:30AM +0100, gabriel.fernandez@...com wrote:
> From: Gabriel Fernandez <gabriel.fernandez@...com>
>
> This patch enables clocks for STM32H743 boards.
>
> Signed-off-by: Gabriel Fernandez <gabriel.fernandez@...com>
> ---
> .../devicetree/bindings/clock/st,stm32h7-rcc.txt | 152 ++
> drivers/clk/Makefile | 1 +
> drivers/clk/clk-stm32h7.c | 1586 ++++++++++++++++++++
> include/dt-bindings/clock/stm32h7-clks.h | 165 ++
> include/dt-bindings/mfd/stm32h7-rcc.h | 138 ++
> 5 files changed, 2042 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/clock/st,stm32h7-rcc.txt
> create mode 100644 drivers/clk/clk-stm32h7.c
> create mode 100644 include/dt-bindings/clock/stm32h7-clks.h
> create mode 100644 include/dt-bindings/mfd/stm32h7-rcc.h
>
> diff --git a/Documentation/devicetree/bindings/clock/st,stm32h7-rcc.txt b/Documentation/devicetree/bindings/clock/st,stm32h7-rcc.txt
> new file mode 100644
> index 0000000..9d4b587
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/st,stm32h7-rcc.txt
> @@ -0,0 +1,152 @@
> +STMicroelectronics STM32H7 Reset and Clock Controller
> +=====================================================
> +
> +The RCC IP is both a reset and a clock controller.
> +
> +Please refer to clock-bindings.txt for common clock controller binding usage.
> +Please also refer to reset.txt for common reset controller binding usage.
> +
> +Required properties:
> +- compatible: Should be:
> + "st,stm32h743-rcc"
> +
> +- reg: should be register base and length as documented in the
> + datasheet
> +
> +- #reset-cells: 1, see below
> +
> +- #clock-cells : from common clock binding; shall be set to 1
> +
> +- clocks: External oscillator clock phandle
> + - high speed external clock signal (HSE)
> + - low speed external clock signal (LSE)
> + - external I2S clock (I2S_CKIN)
> +
> +- st,syscfg: phandle for pwrcfg, mandatory to disable/enable backup domain
> + write protection (RTC clock).
> +
> +- pll x node: Allow to register a pll with specific parameters.
> + Please see PLL section below.
> +
> +Example:
> +
> + rcc: rcc@...24400 {
> + #reset-cells = <1>;
> + #clock-cells = <2>
> + compatible = "st,stm32h743-rcc", "st,stm32-rcc";
> + reg = <0x58024400 0x400>;
> + clocks = <&clk_hse>, <&clk_lse>, <&clk_i2s_ckin>;
> +
> + st,syscfg = <&pwrcfg>;
> +
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + vco1@...24430 {
> + #clock-cells = <0>;
> + compatible = "stm32,pll";
> + reg = <0>;
The reg addr value and unit address don't match.
> + };
> +
> + vco2@...24438 {
> + #clock-cells = <0>;
> + compatible = "stm32,pll";
> + reg = <1>;
> + st,clock-div = <2>;
> + st,clock-mult = <40>;
> + st,frac-status = <0>;
> + st,frac = <0>;
> + st,vcosel = <1>;
> + st,pllrge = <2>;
> + };
> + };
> +
> +
> +STM32H7 PLL
> +-----------
> +
> +The VCO of STM32 PLL could be reprensented like this:
> +
> + Vref --------- --------
> + ---->| / DIVM |---->| x DIVN | ------> VCO
> + --------- --------
> + ^
> + |
> + -------
> + | FRACN |
> + -------
> +
> +When the PLL is configured in integer mode:
> +- VCO = ( Vref / DIVM ) * DIVN
> +
> +When the PLL is configured in fractional mode:
> +- VCO = ( Vref / DIVM ) * ( DIVN + FRACN / 2^13)
> +
> +
> +Required properties for pll node:
> +- compatible: Should be:
> + "stm32,pll"
Only 1 single PLL design for all STM32 chips ever?
> +
> +- #clock-cells: from common clock binding; shall be set to 0
> +- reg: Should be the pll number.
> +
> +Optional properties:
> +- st,clock-div: DIVM division factor : <1..63>
> +- st,clock-mult: DIVN multiplication factor : <4..512>
> +
> +- st,frac-status:
> + - 0 Pll is configured in integer mode
> + - 1 Pll is configure in fractional mode
Isn't this implied by the presence of the next property?
> +
> +- st,frac: Fractional part of the multiplication factor : <0..8191>
> +
> +- st,vcosel: VCO selection
> + - 0: Wide VCO range:192 to 836 MHz
> + - 1: Medium VCO range:150 to 420 MHz
> +
> +- st,pllrge: PLL input frequency range
> + - 0: The PLL input (Vref / DIVM) clock range frequency is between 1 and 2 MHz
> + - 1: The PLL input (Vref / DIVM) clock range frequency is between 2 and 4 MHz
> + - 2: The PLL input (Vref / DIVM) clock range frequency is between 4 and 8 MHz
> + - 3: The PLL input (Vref / DIVM) clock range frequency is between 8 and 16 MHz
Seems like you could figure this out based on the input freq and other
properties.
> +
> +
> +The peripheral clock consumer should specify the desired clock by
> +having the clock ID in its "clocks" phandle cell.
> +
> +All available clocks are defined as preprocessor macros in
> +dt-bindings/clock/stm32h7-clks.h header and can be used in device
> +tree sources.
> +
> +Example:
> +
> + timer5: timer@...00c00 {
> + compatible = "st,stm32-timer";
> + reg = <0x40000c00 0x400>;
> + interrupts = <50>;
> + clocks = <&rcc TIM5_CK>;
> +
> + };
> +
> +Specifying softreset control of devices
> +=======================================
> +
> +Device nodes should specify the reset channel required in their "resets"
> +property, containing a phandle to the reset device node and an index specifying
> +which channel to use.
> +The index is the bit number within the RCC registers bank, starting from RCC
> +base address.
> +It is calculated as: index = register_offset / 4 * 32 + bit_offset.
> +Where bit_offset is the bit offset within the register.
> +
> +For example, for CRC reset:
> + crc = AHB4RSTR_offset / 4 * 32 + CRCRST_bit_offset = 0x88 / 4 * 32 + 19 = 1107
> +
> +All available preprocessor macros for reset are defined dt-bindings//mfd/stm32h7-rcc.h
> +header and can be used in device tree sources.
> +
> +example:
> +
> + timer2 {
> + resets = <&rcc STM32H7_APB1L_RESET(TIM2)>;
> + };
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